Microkeratome with a detachable head

ABSTRACT

A microkeratome that includes a latch assembly that couples a head to a hand piece. The latch assembly allows the head to be readily detached from the hand piece and sterilized. There is no need to also sterilize the hand piece. The microkeratome also has a ring assembly that is coupled to the head and the hand piece. The ring assembly may include a fastener that can be unfastened to allow the hand piece and head to be detached from the ring, even while the ring assembly is fixed to a cornea. The hand piece includes a motor that moves the blade across the ring. The microkeratome may have an aspiration connector with a collar that limits the travel of the blade the and thickness of a resulting lamella flap. The aspiration connector can be replaced with a collar of a different diameter to produce a flap with a different thickness.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a medical device that is used to cut a cornea.

2. Background Information

There have been developed a number of different surgical techniques to correct hyperopic or myopic conditions of a human eye. U.S. Pat. No. 4,840,175 issued to Peyman discloses a procedure wherein a thin layer of a cornea is cut to expose the stroma layer of the cornea. A laser beam is then directed onto the exposed corneal tissue in a predetermined pattern. The laser beam ablates corneal tissue and changes the curvature of the eye. This procedure is sometimes referred to as Laser in situ Keratomileusis (LASIK).

U.S. Pat. No. Re 35,421 issued to Ruiz et al. discloses a device for cutting a cornea in a LASIK procedure. Such a device is commonly referred to as a microkeratome. The Ruiz microkeratome includes a ring that is placed onto a cornea and a blade that is located within an opening of the ring. The device also contains a drive mechanism which moves the blade across the cornea in a first direction while the blade moves in a reciprocating transverse direction to cut the eye. The device can create a lamella flap of the cornea which is flipped back so that the stromal bed of the cornea can be ablated with a laser.

U.S. Pat. No. 6,051,009 issued to Hellenkamp et al. discloses a microkeratome that is sold under the trademark HANSATOME. The HANSATOME microkeratome moves the blade in an arcuate path about the cornea. The HANSATOME includes a disposable blade assembly that can be loaded and removed from the device. The blade assembly includes a blade holder that is attached to a cutting blade. The blade holder has a recess that receives the end of a drive shaft. Rotation of the output shaft moves the blade in an arcuate path, and moves the blade in a back and forth motion to create the lamella flap of the cornea.

Microkeratomes have three primary components, a hand piece that contains a motor, a head that holds the blade, and a ring that applies a suction to maintain the position of the microkeratome relative to the cornea. Because the microkeratome is in contact with patient tissue it must be cleaned after each procedure, typically in an autoclave. The motor and accompanying gears are typically enclosed by a housing of the hand piece. The enclosed nature of the assembly increases the difficulty of cleaning the internal components of the hand piece. Additionally, the autoclave process may degrade the hand piece motor after a number of procedures and cleaning cycles. It would be desirable to provide a microkeratome that does not require the hand piece to be sterilized after each surgical procedure.

The blades used to cut tissue are replaced after each procedure. The replacement blades are typically loaded into the head of the microkeratome with a pair of tweezers. The blade must be loaded accurately so that a drive pin of the motor assembly is inserted into a corresponding slot of a blade holder. Accurately loading the blade with tweezers can be a time consuming process. It would be desirable to provide a blade package that can be used to accurately load a blade into a microkeratome in a time efficient manner.

A complication may occur while the microkeratome is cutting the lamella flap. It may be desirable to remove the microkeratome in the middle of a cut. Removing the microkeratome requires releasing the vacuum of the suction ring. Releasing the vacuum allows the cornea to move back to its original shape. Movement of the cornea will also cause the blade to move. Movement of the blade may cause damage to the cornea. It would be desirable to provide a microkeratome that allows a surgeon to remove a blade while the suction ring is still fixed to the cornea. It would also be desirable to provide a microkeratome that allows the surgeon to vary the thickness of the lamella flap hinge. cl BRIEF SUMMARY OF THE INVENTION

A microkeratome that has a head coupled to a hand piece by a latch assembly. The head holds a blade.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a microkeratome assembly of the present invention;

FIG. 2 is a perspective view of the microkeratome;

FIG. 3 is a top view showing three different aspiration connectors;

FIG. 4 is a sectional view showing a latch assembly of the microkeratome;

FIG. 5 is a sectional view showing motors of the microkeratome;

FIG. 6 is a top sectional view showing a blade being loaded into a head of the microkeratome from a blade shuttle.

DETAILED DESCRIPTION

Disclosed is a microkeratome that includes a latch assembly that couples a head to a hand piece. The latch assembly allows the head to be readily detached from the hand piece and sterilized. There is no need to also sterilize the hand piece. The microkeratome also has a ring assembly that is coupled to the head and the hand piece. The ring assembly may include a fastener that can be unfastened to allow the hand piece and head to be detached from the ring, even while the ring assembly is fixed to a cornea.

The hand piece includes a motor that moves the blade across the ring. The microkeratome may have an aspiration connector with a collar that limits the travel of the blade and the thickness of a resulting lamella flap. The aspiration connector can be replaced with a collar of a different diameter to produce a flap with a different thickness. This allows a surgeon to select a flap hinge thickness.

The blade may be loaded into the microkeratome with a blade shuttle. The blade shuttle may have a plunger that pushes the blade into the microkeratome head. The movement of the plunger may be limited by a stop within the shuttle. The stop assist in accurately locating the blade within the head.

Referring to the drawings more particularly by reference numbers, FIGS. 1 and 2 show an embodiment of a microkeratome 10 of the present invention. The microkeratome 10 includes a hand piece 12 that is connected to a head 14 and a ring assembly 16. The microkeratome 10 is typically used to cut a lamella flap in a cornea as part of a LASIK procedure. The ring assembly 16 may be attached to a source of vacuum to create a suction pressure between the ring and the cornea. The suction pressure fixes the microkeratome to the cornea. The hand piece 12 has a wire assembly 18 that is connected to an electrical console (not shown). The console provides electrical power to actuate the microkeratome 10.

The head 14 has a blade cavity 20 that can receive a blade (not shown). The ring assembly 16 may include a helical gear 22 that is coupled to the hand piece 12. The hand piece 12 includes a motor (not shown) that cooperates with the helical gear 22 to move the head 14 and blade across an opening 24 of the ring assembly 16. The hand piece 12 may contain another motor (not shown) that moves the blade in a lateral reciprocating manner so that the blade cuts corneal tissue and creates a lamella flap. The head 14 and ring assembly 16 may have tongues 26 and grooves 28, respectively, that create linear bearings.

The ring assembly 16 may include a nut 30 that is attached to the helical gear 22. The nut 30 can be removed to allow the hand piece 12 and head 14 to be detached from the ring assembly 16. This allows the hand piece 12, head 14 and blade to be removed even while the ring 16 is applying suction to a cornea. By way of example, the microkeratome 10 may be actuated to initiate cutting of a cornea by the blade. A complication may occur which causes the surgeon to de-actuate the microkeratome and stop the cutting process. Under suction the ring flattens out the cornea. If the suction is removed the cornea may move back to its natural shape. This movement may cause undesirable movement between the blade and corneal tissue. The nut 30 allows the hand piece 12, head 14 and the blade to be removed from the cornea without removing the suction of the ring 16.

The ring assembly 16 may include an aspiration connector 32. The aspiration connector 32 is connected to an aspiration tube (not shown) and is coupled to aspiration openings (not shown) in the ring. The aspiration connector 32 may have a collar 34 that limits the travel of the head 14 and the blade. The aspiration connector 32 may have a threaded shaft (not shown) that screws into a corresponding threaded opening (not shown) of the ring assembly 16.

FIG. 3 shows a plurality of aspiration connectors 32, 32′ and 32″ that each have collars 34, 34′ and 34″. Each collar 34, 34′ and 34″ has a different diameter. The thickness of the lamella flap can be varied by attaching different connectors 32, 32′ or 32″ to the ring assembly 16. For example, connector 32 may create a relatively thin flap. Connector 32′ may create a thicker flap and connector 32″ may create an even thicker flap. The different connectors 32, 32′ and 32″ allow the surgeon to vary the thickness of a lamella flap.

Alternatively, the helical gear 22 can provide a stop function. The stop function may be provided by the end of the threads near the fasterner 30. The stop function could also be provided by a nut attached to the threads of the gear 22. The size of the flap hinge can be varied by changing gears 22.

FIG. 4 shows a latch assembly 40 that connects the head 14 to the hand piece 12. The latch assembly 40 may include a latch 42 that is pivotally connected to the hand piece 12 and fits within a groove 44 of the head 14. The latch assembly 40 may include a return spring 46 that biases the latch 42 into the groove 44.

The latch assembly 40 may further have an actuator 48 that can be depressed by a user to move in a downward direction as indicated by the arrow to rotate the latch out of the groove 44. The assembly 40 may include a return spring(s) 50 to move the actuator 48 back when released by the user. As shown in FIG. 1, the actuator 48 may be located on a first face 52 of the hand piece 12.

A user can attach the head 14 to the hand piece 12 by moving the head 14 until the latch 42 snaps into the groove 44. The head 14 can be removed from the hand piece 12 by depressing the actuator 48 to pull the latch 42 out of the groove 44. The head 14 then be sterilized and re-attached to the hand piece 12. Alternatively, the head 14 may be replaced. By way of example, the head 14 may be constructed from a low cost plastic material that is replaced after every procedure. The hand piece 12 may also be constructed from a plastic material. The head may be constructed from the same plastic material as the hand piece. By way of example, the plastic may be a polycarbonate or polysulphone.

FIG. 5 shows a pair of motor assemblies 60 and 62 within the hand piece 12. Motor assembly 60 may move the blade in a lateral reciprocating manner. Motor assembly 62 may be coupled to the helical gear of the ring assembly to pull the head and blade across the ring opening.

As shown in FIG. 6 a blade 70 may be packaged within a blade shuttle 72. The blade shuttle 72 may include a housing 74 that holds the blade 70 and a plunger 76 that can be operated to push the blade 70 into the head 14. The shuttle 72 may have an alignment pin (not shown) that is inserted into a corresponding alignment hole (not shown) of the head 14 to align the blade 70 with the head cavity. The housing 74 may include a stop (not shown) that limits the travel of the plunger 76 and the location of the blade within the head 14. The stop provides a feature that allows for the blade to be accurately located within the head cavity in a repeatable manner. It is desirable to accurately locate the blade within the blade cavity so that a pin (not shown) of the motor assembly is coupled to a corresponding slot (not shown) of the blade.

While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art. 

1. A microkeratome assembly, comprising: a hand piece that has a latch assembly; a head that is connected to said hand piece by said latch assembly; and, a blade coupled to said head.
 2. The microkeratome of claim 1, wherein said latch assembly includes a latch that fits within a groove of said head.
 3. The microkeratome of claim 1, wherein said latch assembly includes a return spring connected to said latch.
 4. The microkeratome of claim 2, wherein said latch assembly includes an actuator that moves said latch.
 5. The microkeratome of claim 4, wherein said latch assembly includes a return spring connected to said actuator.
 6. The microkeratome of claim 1, wherein said hand piece include a motor that is coupled to said blade.
 7. The microkeratome of claim 2, wherein said latch assembly includes an actuator that is located on a front face of said hand piece.
 8. The microkeratome of claim 1, wherein said head and said hand piece are constructed from a plastic material.
 9. A microkeratome assembly, comprising: a hand piece; a head; a blade coupled to said head; and, latch means for connecting said head to said hand piece.
 10. The microkeratome of claim 9, wherein said latch means includes a latch that fits within a groove of said head.
 11. The microkeratome of claim 10, wherein said latch means includes a return spring connected to said latch.
 12. The microkeratome of claim 11, wherein said latch means includes an actuator that moves said latch.
 13. The microkeratome of claim 12, wherein said latch means includes a return spring connected to said actuator.
 14. The microkeratome of claim 9, wherein said hand piece include a motor that is coupled to said blade.
 15. The microkeratome of claim 9, wherein said latch means includes an actuator that is located on a front face of said hand piece.
 16. The microkeratome of claim 9, wherein said head and said hand piece are constructed from a plastic material.
 17. A method for attaching a head of a microkeratome to a hand piece, comprising: pushing the head into the hand piece until a latch assembly connects the head to the hand piece.
 18. The method of claim 17, wherein a latch of the latch assembly moves into a groove of the head.
 19. The method of claim 17, wherein an actuator is depressed to disengage the latch assembly and allow the head to be disconnected from the hand piece.
 20. A microkeratome assembly, comprising: a hand piece; a head that is connected to said hand piece; a blade coupled to said head; a ring assembly coupled to said hand piece; and, a fastener that is attached to said ring assembly and can be removed to allow said hand piece, said head and said blade to be detached from said ring assembly.
 21. The microkeratome of claim 20, wherein said fastener is a nut that attaches to a helical gear of said ring assembly, said helical gear being coupled to a motor of said hand piece.
 22. The microkeratome of claim 20, wherein said ring assembly includes a helical gear that limits a travel of said head and said hand piece.
 23. A method for detaching a hand piece from a ring assembly of a microkeratome, comprising: removing a fastener from a ring assembly that is connected to a hand piece, a head and a blade; and, detaching the hand piece, the head and the blade from the ring assembly.
 24. The method of claim 23, wherein the hand piece is detached while the ring assembly is attached to a cornea.
 25. A microkeratome assembly, comprising: a head; a blade coupled to said head; a ring assembly coupled to said head; a hand piece that is coupled to said head and moves said blade relative to said ring assembly; a first aspiration connector that can be attached to said ring assembly, said first aspiration connector having a collar that limits a travel of said blade to a first distance; and, a second aspiration connector that can be attached to said ring assembly, said second aspiration connector having a collar that limits a travel of said blade to a second distance.
 26. The microkeratome of claim 25, wherein said collar of said first aspiration connector has a first diameter and said collar of said second aspiration connector has a second diameter.
 27. A method for varying the size of a corneal flap created by a microkeratome, comprising: detaching a first aspiration connector from a ring assembly that is coupled to a head, a hand piece and a blade that can move relative to the ring assembly, the first aspiration connector having a first collar; attaching a second aspiration connector to the ring assembly, the second aspiration connector having a second collar; and, moving the blade until movement of the blade is limited by the second collar.
 28. The method of claim 27, wherein the first collar has a first diameter and the second collar has a second diameter. 